6026-02-4Relevant academic research and scientific papers
Aminosilyl-Substituted Diarylethene Compounds for Anionic Polymerisation
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Paragraph 0183-0188, (2017/08/07)
The invention related to novel compounds useful as modifying monomers and precursors for polymerization initiators. The invention further relates to a method of making the polymerization initiators and resulting polymers. The invention also relates to pol
2′-Alkynylnucleotides: A Sequence- and Spin Label-Flexible Strategy for EPR Spectroscopy in DNA
Haugland, Marius M.,El-Sagheer, Afaf H.,Porter, Rachel J.,Pe?a, Javier,Brown, Tom,Anderson, Edward A.,Lovett, Janet E.
supporting information, p. 9069 - 9072 (2016/08/05)
Electron paramagnetic resonance (EPR) spectroscopy is a powerful method to elucidate molecular structure through the measurement of distances between conformationally well-defined spin labels. Here we report a sequence-flexible approach to the synthesis of double spin-labeled DNA duplexes, where 2′-alkynylnucleosides are incorporated at terminal and internal positions on complementary strands. Post-DNA synthesis copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions with a variety of spin labels enable the use of double electron-electron resonance experiments to measure a number of distances on the duplex, affording a high level of detailed structural information.
Flexible stereoselective functionalizations of ketones through umpolung with hypervalent iodine reagents
Mizar, Pushpak,Wirth, Thomas
supporting information, p. 5993 - 5997 (2014/06/10)
The functionalization of carbonyl compounds in the α-position has gathered much attention as a synthetic route because of the wide biological importance of such products. Through polarity reversal, or "umpolung", we show here that typical nucleophiles, such as oxygen, nitrogen, and even carbon nucleophiles, can be used for addition reactions after tethering them to enol ethers. Our findings allow novel retrosynthetic planning and rapid assembly of structures previously accessible only by multistep sequences. A Nu approach: An efficient α-functionalization of ketones with a range of simple and useful nucleophiles is possible by using hypervalent iodine reagents (see scheme; Nu′ can be the Nu itself or a protected form of this nucleophile group).
Regioselective synthesis of multisubstituted benzenes by palladium-catalyzed intermolecular reaction of β-iodo-β-silylstyrenes with alkynes
Kinoshita, Hidenori,Takahashi, Hirotoshi,Miura, Katsukiyo
supporting information, p. 2962 - 2965 (2013/07/26)
The Pd-catalyzed reaction between β-iodo-β-silylstyrenes and terminal alkynes in i-Pr2NEt gave 1,2,3,5-tetrasubstituted benzenes with complete regioselection. The use of certain silylacetylenes as alkynes enabled efficient synthesis of 1,3,5-trissilyl-2-arylbenzenes, which could be transformed into other multisubstituted benzenes by displacement of the silyl groups.
Selective synthesis of functional alkynylmono- and -trisilanes
Hoffmann, Florian,Wagler, Joerg,Roewer, Gerhard
scheme or table, p. 1133 - 1142 (2010/06/20)
The selective synthesis of functional alkynylsllanes RC=C(SiMe 2)m,-X (m = 1, 3) was investigated. Monofunctionalization with or without protecting groups gave moderate to good yields of alkynyldimethylmonosilanes RC=CMe2SiX [R = Ph, X = Cl. (1), NEt 2 (2), OMe (3), H (4), Br (5), I (6), Cp (8), C5H 4Li (10), Ph (11); R = Pr, X = Ph (12)]. Compounds 4 and 8 were converted into the (alkyne)transition-metal complexes 4-Cp2Mo 2(CO)4 (13) and 8-Co2(CO)6 (14), respectively, which were characterized by X-ray diffraction. Stepwise extension and functionalization of the silane chain starting from 1chloro-2-(diethylamino) tetramethyldisilane (Et2NMe2Si-SiMe2Cl) yielded the trisilanes Ph-(SiMe2J3-X [X = NEt2 (18), OMe (19), Cl (20), H (21), C=CPh (22), C=CPr (23)]. The synthesized compounds were characterized by NMR and IR spectroscopy, 4, 11, 13, and 14 also by UV/Vis spectroscopy.
Arylsilane oxidation - New routes to hydroxylated aromatics
Bracegirdle, Sonia,Anderson, Edward A.
supporting information; experimental part, p. 3454 - 3456 (2010/07/16)
An efficient route to hydroxylated aromatics has been developed, via the oxidation of aryl organosilanes under functional group-tolerant and relatively mild conditions, using sub-stoichiometric amounts of fluoride promoters.
Temporary silicon connection strategies in intramolecular allylation of aldehydes with allylsilanes
Beignet, Julien,Jervis, Peter J.,Cox, Liam R.
, p. 5462 - 5475 (2008/12/21)
(Chemical Equation Presented) Three γ-(amino)silyl-substituted allylsilanes 14a-c have been prepared in three steps from the corresponding dialkyldichlorosilane. The aminosilyl group has been used to link this allylsilane nucleophile to a series of β-hydroxy aldehydes through a silyl ether temporary connection. The size of the alkyl substituents at the silyl ether tether governs the outcome of the reaction on exposure to acid. Thus, treatment of aldehyde (E)-9aa, which contains a dimethylsilyl ether connection between the aldehyde and allylsilane, with a range of Lewis and Bronsted acid activators provides an (E)-diene product. The mechanism of formation of this undesired product is discussed. Systems containing a sterically more bulky diethylsilyl ether connection react differently: thus in the presence of TMSOTf and a Bronsted acid scavenger, intramolecular allylation proceeds smoothly to provide two out of the possible four diastereoisomeric oxasilacycles, 23 (major) and 21 (minor). A diene product again accounts for the remaining mass balance in the reaction. This side product can be completely suppressed by using a sterically even more bulky diisopropylsilyl ether connection in the cyclization precursor, although this is now at the expense of a slight erosion in the 1,3-stereoinduction in the allylation products. The sense of 1,3-stereoinduction observed in these intramolecular allylations has been rationalized by using an electrostatic argument, which can also explain the stereochemical outcome of a number of related reactions. Levels of 1,4-stereoinduction in the intramolecular allylation are more modest but can be significantly improved in some cases by using a tethered (Z)-allylsilane in place of its (E)-stereoisomer. Oxidation of the major diastereoisomeric allylation product 23 under Tamao-Kumada conditions provides an entry into stereodefined 1,2-anti-2,4-syn triols 28.
Using a Temporary Silicon Connection in Stereoselective Allylation with Allylsilanes: Application to the Synthesis of Stereodefined 1,2,4-Triols
Beignet, Julien,Cox, Liam R.
, p. 4231 - 4234 (2007/10/03)
(Equation presented) Treatment of aldehyde 6 with TMSOTf, in the presence of a Bronsted acid scavenger, effects an intramolecular allylation to provide the oxasilacycle 7 as the major diastereoisomer. Tamao oxidation of the C-Si bond in 7 affords the corresponding 1,2,4-triol 9.
A novel route to chlorodimethylsilane
Chrusciel
, p. 1405 - 1411 (2007/10/03)
A new efficient laboratory method of preparation of chlorodimethylsilane (Cl(CH3)2SiH) has been elaborated, which is a modification of the Eaborn et al. method (34) and is based on a transsilylation reaction of substituted (amino)dimethylhydrosilanes, R2NSiMe2H (R2 = Me2, Et2, (CH2)n, etc.) with dimethyldichlorosilane (Me2SiCl2). The reaction proceeds at reflux, at 70°C, preferably with an excess of Me2SiCl2. The most important feature of this novel method is a recovery of intermediate (amino)chlorodimethylsilanes (R2NSiMe2Cl), which can be again reduced to R2NSiMe2H. The transsilylation mechanism has been proven by reaction of (diethylamino)methylphenylsilane with Me2SiCl2. The products of this latter reaction are HMePhSiCl and R2NSiMe2Cl, thus a disproportionation mechanism has been excluded. New substituted bis(amino)dimethylsilanes ((R2N)2SiMe2), (amino)dimethylchlorosilanes (R2NSiMe2Cl), and (amino)dimethylhydrosilanes (R2NSiMe2H) have been synthesized and characterized by NMR and IR.
